Combustion chamber cooling

ABSTRACT

A gas turbine combustion chamber ( 8 ) surrounded by an inner wall ( 2 ) having cooling air bores ( 17 ) and an outer wall ( 9 ) that is spaced from the inner wall ( 2 ). The outer wall ( 9 ) likewise has cooling air bores ( 16 ) and is formed of a plurality of wall elements ( 11 ) that are arranged in the circumferential direction of the gas turbine combustion chamber ( 8 ) essentially next to each other. The outer wall elements are arranged on the inner wall ( 2 ) by means of a fixed bearing ( 24 ) on one narrow side ( 21 ) of a wall element and by means of a floating bearing ( 25 ) on an opposite narrow side ( 21 ) of the element, configured to define a hollow space ( 10 ) is formed between the two walls ( 2, 9 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 35 U.S.C. §§371 national phase conversion of PCT/EP2013/062148, filed Jun. 12, 2013, which claims priority of German Patent Application No. 10 2012 213 637.1, filed Aug. 2, 2012, the contents of which are incorporated by reference herein. The PCT International Application was published in the German language.

The present invention relates to a gas turbine combustion chamber.

Combustion chambers, in particular for gas turbines, are generally provided, internally, with a flow guiding body, called a liner. A combustible fluid is supplied via one or more burners provided in the combustion chamber, which fluid ignites in the combustion space of the combustion chamber and, passing through the liner, is guided towards the outlet opening. Since the walls of the combustion chamber are subjected to high thermal loads due to the combustion taking place inside the combustion chamber, these parts of the combustion chamber have to be cooled. A thermal barrier coating on the inside of the liner is generally not sufficient. Cooling is achieved e.g. by means of interstices through which is conveyed a coolant which cools the combustion chamber convectively.

The components experience thermal expansion caused by temperature changes which occur during operation.

The liner simultaneously represents the transition to the turbine space and is therefore conical. The cooling system must be able to cope with the axial and radial thermal expansion of the liner cone and must ensure that, even in the case of changing conditions, only a certain defined quantity of air flows along the cone.

FIG. 1 shows a gas turbine combustion chamber with convective cooling of the liner cone which is provided with an external sheath.

SUMMARY OF THE INVENTION

The invention has the object of providing a gas turbine combustion chamber with improved cooling.

A gas turbine combustion chamber has an inner wall with cooling air bores circumferentially around it and an outer wall around and spaced apart from the inner wall. The outer wall also has cooling air bores. The outer wall is formed from multiple wall elements which are arranged substantially next to one another in the circumferential direction of the gas turbine combustion chamber. By substantially is here meant that the wall elements can move closer or move apart as operating temperature affects them, but are close together enough to enable a common fastener to hold neighboring opposing edges with a common fastener, if that is selected. The wall elements are arranged on the inner wall by means of a respective fixed bearing on one narrow side of each wall element and by means of a floating bearing on an opposite narrow side of each wall element, such that a cavity is formed between the inner and outer walls. The outer wall cone is cooled by an effective impingement cooling. Furthermore, the outer wall elements, which act as impingement cooling plates, are allowed to expand relative to the main body, i.e. the inner wall of the gas turbine, as a consequence of different temperatures of the main body (approx. 900-1000° C.) and of the impingement cooling plates (approx. 500-600° C.)

In one advantageous embodiment, the wall elements are arranged on the inner wall by means of a fixed bearing on the burner side and by means of a floating bearing on the turbine side.

It is then expedient if the inner wall is in the form of a hollow frustum and the wall elements of the outer wall are in the form of hollow frustum segments.

In order to better compensate for the thermal expansion in the radial direction, adjacent outer wall elements are arranged such that they overlap.

In one advantageous embodiment, for easier assembly the floating bearing is comprised of ring segments each of which has a groove for receiving in each case one narrow side of the wall elements.

Expediently, the fixed bearing also is comprised of ring segments.

For cooling the bearings, at least one of the bearings has cooling air bores.

In order to prevent adjacent wall elements separating, it is advantageous if retainers are provided in the region where the edges of two neighboring wall elements overlap. It can then be expedient if the retainers are attached to the inner wall.

In order to permit different thermal expansions in as stress-free a manner as possible, also at the retainers, the wall elements have openings for the retainers, wherein the diameters of the openings are larger than the diameters of the retainers in this region.

In order to prevent the wall elements of the outer wall touching the cone of the inner wall because of thermal deformation, spacers (pins) are arranged between the inner wall and the outer wall. These spacers are expediently arranged, for example welded, on the inner wall opposite a central region of the respective wall element, i.e. in the middle beneath the wall elements.

An embodiment of the cavity formed by the inner wall and the outer wall as an acoustic damper (resonator) is particularly advantageous since it is thus possible to reduce the number of resonators which would otherwise be required. On one hand, this reduces costs and, on the other hand, it saves air which would otherwise be required for flushing or cooling these resonators.

The advantages of the proposed solution reside in the improved cooling of the liner cone by means of an effective impingement cooling, and in the avoidance of the thermal stress which results through the floating bearing. In addition, the cavity created between the liner cone and the plates, which cavity also acts as a resonator, damps medium- to high-frequency vibrations.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail by way of example with reference to the drawings, which are schematic and not to scale and in which:

FIG. 1 shows a gas turbine combustion chamber with a burner liner according to the prior art with an external sheath for convective cooling,

FIG. 2 shows a gas turbine combustion chamber according to the invention with wall elements for impingement cooling,

FIG. 3 shows a wall element with cooling air bores and openings for attachment,

FIG. 4 shows a detail of a fixed bearing ring segment,

FIG. 5 shows a section through a burner liner of a gas turbine combustion chamber according to the invention with a fixed bearing,

FIG. 6 shows a section through a burner liner of a gas turbine combustion chamber according to the invention with a floating bearing,

FIG. 7 shows a plan view of a ring segment of the floating bearing,

FIG. 8 shows a gas turbine combustion chamber according to the invention without wall elements,

FIG. 9 shows a bolt for retaining the wall elements and preventing them separating,

FIG. 10 shows a bolt in the installed state with wall elements and

FIG. 11 shows overlapping wall elements.

DESCRIPTION OF EMBODIMENTS

FIG. 1 shows, schematically and by way of example, a gas turbine combustion chamber 1 according to the prior art with an inner wall 2 (burner liner) which encloses the combustion space 3 and has, on the combustion space side, a thermal protection coating 4, and a sheath 5 surrounding the inner wall 2. Between the inner wall and the sheath 5, cooling air 6 is guided for convectively cooling the inner wall 2. In the transition from the combustion space 3 downstream to the turbine space (not shown), the gas turbine combustion chamber 1 and therefore also the inner wall 2 or the burner liner 2 are conical. This region is therefore also termed the liner cone 7.

FIG. 2 shows a gas turbine combustion chamber 8 according to the invention with an inner wall 2 and an outer wall 9 spaced apart therefrom, which form a cavity 10 (see FIGS. 5 and 6). The outer wall 9 is formed by a plate construction, comprised of eight wall elements 11, which are configured and arranged and supported to compensate for thermal expansion of the liner cone 7. The number of wall elements 11 can differ from that shown in the exemplary embodiment of FIG. 2.

The wall elements 11 are welded to the inner wall 2 on that side 12 of the liner cone 7 which is oriented towards the burner, that is towards the base of the frustum, and are mounted in a floating manner on that side 13 of the liner cone 7 which is oriented towards the turbine, that is towards the top of the frustum. However, the solution may also be reversed.

In that context, two plate rows 14, 15 are installed offset on top of one another. For the purpose of impingement-cooling of the inner conical wall 2 the outer wall elements 11 have cooling air bores 16. Corresponding cooling air bores 17 are provided in the inner wall 2 (see FIGS. 8 and 10) such that the air used for the impingement cooling can flow into the combustion space 3.

FIG. 3 shows an outer wall element 11 with cooling air bores 16. During operation, gaps could emerge between superposed wall elements 11, through which air could penetrate uncontrolled under the plate construction. However, these gaps are avoided by means of retainers 18 (see FIGS. 10-11). To that end, the wall elements 11 have openings 20 on two opposite axial sides 19. The diameter of these openings is larger than the retainer diameter in this region in order to guarantee, here too, sufficient play for thermal expansion. The two other circumferential sides 21 together form, with the ring segments 22, 23 shown in FIGS. 4 to 7, a fixed bearing 24 and a floating bearing 25.

FIG. 4 shows a detail of a fixed bearing 24, in particular a detail comprised of a ring segment 22 for a fixed bearing 24. If the ring segment 22 is welded to the inner wall 2 (see FIG. 5), a cavity 26 is formed which can be cooled via cooling air bores 27 in the ring segment 22.

FIG. 5 shows a section through a fixed bearing 24 of a gas turbine combustion chamber 8 according to the invention with a ring segment 22 for the fixed bearing 24, which ring segment is arranged on the burner liner 2 and is connected thereto at the welding points 28, and adjacent wall elements 11 which are arranged offset in the axial direction of the combustion chamber 8. The wall elements 11 are connected to the ring segment 22 at the welding points 29. For assembly reasons, adjacent wall elements 11 are welded to the ring segments 22 offset in the axial direction.

FIG. 6 shows a section through a floating bearing 25 of a gas turbine combustion chamber 8 according to the invention with a ring segment 23 for the floating bearing 25, which ring segment is arranged on the burner liner 2 and is connected thereto at the welding points 30. The ring segment 23 of the floating bearing 25 comprises a groove 31 for receiving a narrow side 21 of the wall elements 11 and bears directly against the inner wall 2 such that cooling air bores in the ring segment 23 are also not necessary.

FIG. 7 shows a ring segment 23 for the floating bearing 25. The groove 31, for mounting the wall elements 11 in a floating manner in the ring segment 23, runs according to the overlapping arrangement of the wall elements 11 at various radii with overlapping regions 32.

FIG. 8 shows a gas turbine combustion chamber 8 according to the invention without wall elements 11. It is thus possible to see bolts 33, as parts of the separation-preventing retainers 18, and also other spacers or pins 34 which are arranged on the inner wall 2 and which prevent the wall elements 11 touching the cone of the inner wall 2 because of thermal deformation. The pins 34 are typically welded to the inner wall 2, in the middle beneath the wall elements 11.

FIG. 9 shows a bolt 33 with a further formed element for simpler assembly on the inner wall 2. The bolt 33 is part of a retainer 18 as is used to prevent separation between two adjacent wall elements 11.

FIG. 10 shows such a retainer 18 in the installed state. It is welded to the inner wall 2 and may be arranged on the inner wall 2 in a depression 35 provided for that purpose. In the region of the openings 21 of the wall elements 11, the diameter of the bolt 33 of the retainer 18 is smaller than that of the openings 21 themselves, such that sufficient space for thermal expansion is present. The wall elements 11 are secured by means of a perforated disk 36 welded thereto, such that essentially only axial displacements of the wall elements 11 and displacements in the circumferential direction of the gas turbine combustion chamber 8, but no radial movements, are possible. FIG. 11 shows a plan view of the region of the retainer 18.

Although a gas turbine combustion chamber with a conical surrounding inner wall has been described in the exemplary embodiments, the invention is not restricted to a conical shape. Furthermore, the function of the device according to the invention is not restricted to a cooling effect to be achieved, but can also be used as a resonance absorber. 

1. A gas turbine combustion chamber comprising: an inner wall around the chamber, first cooling air bores through the inner wall; an outer wall around and spaced above the inner wall, second cooling air bores through the outer wall; the outer wall is formed from multiple separate wall elements which are arranged substantially next to one another in the circumferential direction of the gas turbine combustion chamber, the wall elements having opposite, axially extending, narrow sides and are spaced above the inner wall; a respective fixed bearing located on one of the narrow sides of each wall element and supporting the respective narrow side of the wall element on and spaced above the inner wall and the fixed bearing being configured to hold the wall element against shifting circumferentially; and a floating bearing on the opposite narrow side of each of the wall elements, the fixed and floating bearings being configured to support the neighboring wall elements with respect to the inner wall such that a cavity is formed between the inner and outer walls; and adjacent wall elements are arranged such that they overlap in the circumferential direction.
 2. The gas turbine combustion chamber as claimed in claim 1, wherein the outer wall elements are supported on and located above the inner wall by the fixed bearing toward a burner side of the wall elements and by the floating bearing on the turbine side of the wall elements.
 3. The gas turbine combustion chamber as claimed in claim 1, wherein the inner wall is in the form of a hollow frustum and the wall elements are in the form of hollow frustum segments.
 4. The gas turbine combustion chamber as claimed in claim 1, wherein the floating bearing is comprised of ring segments which each have a groove located and configured for receiving one narrow side of adjacent ones of the wall elements and the groove is configured to allow the respective narrow sides received in the respective groove to move in the groove due to temperature variation.
 5. The gas turbine combustion chamber as claimed in claim 1, wherein the fixed bearing is comprised of ring segments around the inner wall.
 6. The gas turbine combustion chamber as claimed in claim 2, wherein at least one of the bearings has cooling air bores.
 7. The gas turbine combustion chamber as claimed in claim 1, further comprising retainers located in the region where each two adjacent wall elements overlap and configured to prevent the two adjacent wall elements from separating.
 8. The gas turbine combustion chamber as claimed in claim 7, wherein the retainers are attached to the inner wall.
 9. The gas turbine combustion chamber as claimed in claim 8, further comprising the wall elements have openings for the retainers to extend through the openings, and diameters of the retainer openings in each two adjacent wall elements are larger than the diameters of the retainers for their adjacent wall elements.
 10. The gas turbine combustion chamber as claimed in claim 1, further comprising spacers between the inner wall and the outer wall located to prevent contact between the inner and outer walls.
 11. The gas turbine combustion chamber as claimed in claim 10, wherein the spacers are arranged on the inner wall and located opposite a central region of the respective wall element.
 12. The gas turbine combustion chamber as claimed in of claim 1, wherein a cavity is formed between the inner wall and the outer wall and is embodied as an acoustic damper.
 13. The gas turbine combustion chamber as claimed in claim 2, wherein the floating bearing receives the narrow axial sides of each two neighboring outer wall elements to overlap in the floating bearing.
 14. The gas turbine combustion chamber as claimed in claim 3, wherein the floating bearing of each outer wall element is toward a wider end of the frustum and the fixed bearing of each outer wall element is toward a narrow end of the frustum.
 15. The gas turbine combustion chamber as claimed in claim 2, wherein the fixed bearing is welded to the inner wall. 